This is why a lone wolf, some years ago, they indicated was the only thing that concerned them. They have the ability in almost real time to detect one person communicating to another an ill intent or specific threat of harm. That's why you read these stories about some person making a threatening facebook or twitter post with sufficient specificity and then the fuzz show up at his door just two or three hours later. It takes less than an hour for them to become aware of any such communication.

The only thing they consider a threat is what goes on inside your head because everything else, everything you've voiced on the phone, typed online, searched for, ordered or Thumbed Up, talked to, or planned to meet, they already know.